Document Type

Technical Report

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Technical Report Number



General purpose middleware has been shown to be effective in meeting diverse functional requirements for a wide range of distributed systems. Advanced middleware projects have also supported a single quality-of-service dimension such as real-time, fault tolerance, or small memory footprint. However, there is limited experience supporting multiple quality-of-service dimensions in mid-dleware to meet the needs of special purpose applications. Even though general purpose middleware can cover an entire spectrum of applications by supporting the union of all features required by each application, this approach breaks down for distributed real-time and embedded systems. In particular, features from one dimension such as real-time may interfere with requirements for another dimension such as fault tolerance. Furthermore, the breadth of features supported may interfere with small memory footprint requirements. In this paper, we document the results of our experiences developing special purpose middleware for an emerging class of systems: networked embedded sensors. We make two contributions to the state of the art in customized middleware for distributed real-time and embedded applications. First, we demonstrate that reduced foot-print can be achieved while maintaining or even improving real-time properties. Second, we give evidence that empirical measurement using a representative application is crucial to guide selection of feature subsets from gen-eral purpose middleware.


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